Certainly I don't need a floppy drive, (although ebay has tons of external and internal floppy drives cheap), I got all my stuff off of floppies in the nineties. They had so little space (even the 1.44MB ones), that you couldn't put an album on one. I haven't had to consider that for many builds. (So sorry for those of you who find a shoe box of floppies with things that you don't know if you need.)
A cdrom, though, can hold an album. A dvd drive can hold a movie. Nothing smaller can serve those purposes. I don't know if you remember, but they have evolved as well. They went one side, two side, single layer, double layer until they became pretty much perfect for their use. They can hold any conceivable movie or album.
Certainly a USB thumb drive can hold either and more, but it has one big drawback. It isn't flat. It has to be at least as thick as an USB connector and be long enough to let you grab it to plug it in or pull it out. I have some that are that minimum size physically, (see the picture above), and are 32GB. They didn't cost much, but already they have already gone the way of the dodo. You can buy larger ones (in storage capacity), for less than they originally cost.
I suppose that a ukulele tutorial book could come with a blister on the front with a usb drive in it, and maybe that will be what will happen. It hasn't happened yet, but it might, clearly. Any modern machine can read a usb thumb drive. It is a good standard for something like this. Even if you have a modern machine that disdains USB 2.0 or 1.0 in favour of USB 3.0 or 3.1, they are backward compatible. You can plug those old and small and slow ones in, and they will work.
It is, clearly though, a poorer solution in the sense that it can't be as flat as the magazine or book. It has to be at least as thick as a USB connector to plug in. That means that publishers can't fit as many books in a box. Shipping will cost more.You might not want to ship it in a magazine or a tutorial book, especially not in a beginner's book that is way thinner than a USB drive.
I suppose that just like OSes today, things might start shipping on thumb drives, (you can get Windows 10 on a thumb drive), and of course I love getting free thumb drives as long as they aren't too small. Right now, I tend to buy 64GB and up thumb drives, they don't cost much, but soon they too will be to small a capacity to sell.
If you gave me a thumb drive that would just barely hold an album -- I would just throw it away. I would feel bad about the waste, and of the harm to the environment, but what would I do with it? It is obsolete already. I have plenty of thumb drives that are way bigger than that that either cost me very little money or were in fact free (thank you marketing folks), to serve all of my needs.
I use everything. I am an uber-geek. I was and am using everything before most people have it on their radar -- all the way back to the internet way before the web, but I still don't see what can replace an optical disk. Clearly there is a need for something that is high capacity and flat, but there is nothing that has been settled on.
There are things, multiple things that fit our criteria, things that have large capacity and are flat. I am talking about things like memory cards, SD cards. (SD stands for Secure Data which was originally about encrypting music -- Hmmm.) Nowadays they are mostly used in cameras and phones. Recently, they are being replaced by SDHC and SDXC cards with more storage available on them. Bigger. Better. They use the same technology as is used in a thumb drive, (or a flash drive), i.e. memory that can be read and written, but they come in a flatter package.
Right now, most computers do not have readers for them, although more, (most?), laptops do. The problem is that there is no recognized single standard. An external or internal card reader feels that they have to support CF I/II/MD, Micro SD, SD/SDHC/SDXC/MMC/RSMMC, MS/MS PRO/MS PRO DUO, M2(MS MICRO). To make it even more complicated, many of these come in the original, the mini, and in micro sizes. Whew! Your phone almost certainly uses some size of them. But seriously, can't we just pick one that is tiny and holds terabytes? (SDXC supports up to 2TB, SDHC 32GB, and SD 4GB.)
What if your guitar or piano instructional book came with a memory card that your hardware didn't support, one that was just newer than your computer could understand? Suppose that you didn't have a card reader at all? They aren't ubiquitous. There is, yet, no clear winner. Even on cameras or phones (where these things are king), many times there are more than one slot because they admit that people want to use more than one thing. It hasn't settled out. That's the problem. There is no one winner.
As an example, a camera I would love to have, the Canon EOS-1d Mark IV (you can buy it for me if you are rich please), says that it supports: CF Card Type I and II and SD/SDHC Memory Card (1 slot each). Those are completely different and incompatible beasts (hence needing different slots). A SDXC card won't even work although wouldn't you wish for 2TB of storage on your camera?
So to wrap it up, I will just say that this is a problem that has not been solved in any way that is workable for a joe q citizen like me. There is still nothing that is as ubiquitous as an optical drive to distribute media on. I hope for it, and I will adopt it before you will most likely, but it doesn't exist today. People are still distributing things I want on optical disks. Clearly I still need an optical reader on my next build (and a crazy multiple card reader).
Edit: my final build that I'm typing this on now is:
1x Corsair 450D Mid tower E-ATX, ATX, mini-ATx and micro-ATX $119-$129
1x i7-6700K CPU
1x ASRock Z170 OC Formula LGA 1151 Motherboard
1x G.SKILL TridentZ Series 64GB (4 x 16GB) 288-Pin DDR4 SDRAM DDR4 3200
(PC4 25600) Desktop Memory Model F4-3200C14Q-64GTZ
1x SeaSonic Snow Silent-1050 1050W ATX12V / EPS12V
80 PLUS PLATINUM Certified Full Modular Active PFC Power Supply
1x ZOTAC GeForce GTX 980 Ti 6GB AMP! Extreme graphics card
3x SAMSUNG 950 PRO M.2 SSD
512GB PCI-Express 3.0 x4 Internal Solid State Drive (SSD) MZ-V5P512BW
3x Western Digital RE WD6001FXYZ HDD
6TB 7200 RPM 128MB Cache SATA 6.0Gb/s 3.5" Datacenter Capacity HDD
1x Microsoft Windows 10 Pro - Full Version (32 & 64-bit) / USB Flash Drive
1x NZXT Kraken X61 RL-KRX61-01
280mm All-In-One Water / Liquid CPU Cooling Solution
1x LG Black Blu-ray Burner SATA WH16NS40 - OEM with an external usb case
1x Akasa AK-HC-07BK Card Reader
4 USB 3.0 + 2xUSB charging (no data)
Smart Card (bank cards, access cards, based on ISO7816 implementation)
Compact Flash (CF I, CF II, Ultra, Extreme, I-Pro, Ultimate, MD)
Memory Stick (MS Pro, MS Pro Duo, Magic Gate, Extreme, Ultra)
Secure Digital (SDXC, SDHC, SD, Ultra, Extreme, Elite Pro, High Speed,
MMC, MMC Mobile)
• 128GByte for SDXC • 32GByte for SDHC
M2 (Memory Stick Micro M2)
microSD (microSDHC, micro SDXC, High Capacity)
1x Dell 27 UltraHD 4K Monitor - P2715Q
1x Corsair K95 RGB Mechanical Gaming Keyboard with CHERRY MX Brown Switches
1x Logitech G900 RF Wireless/Wired optical mouse with free spin wheel
1x BOSE Companion 2 Series III Multimedia Speaker System
1x HyperX Cloud II Gaming Headset with 7.1 Virtual Surround Sound
for PC/PS4/Mac/Mobile - Red
1x Wacom Intuos Pro PTH651 8.8" x 5.5" Active Area USB Pen and Touch Medium
1x Epson SureColor P600 printer